Antioxidant activity of wine assessed by different in vitro methods

Epidemiological studies have suggested that a diet rich in antioxidant compounds could help in counteracting the effects of reactive oxygen species, reducing the risk factors for chronic diseases. The moderate consumption of wine, especially red wine, has been associated with the reduction in mortalities from cardiovascular diseases. One of the possible reasons for the protective effect of wine can be identified in the high content of polyphenols (mainly flavonoids), which have significant antioxidant activity. Even though several in vitro tests have been developed for the measure of the antioxidant property, no method has showed a satisfactory correlation with the in vivo situation. On these bases, the aim of this study was the application and comparison of different in vitro methods to assess the antioxidant activity of red, rose and white wines. The methods were: 1) Folin-Cocalteau's assay for the quantification of total polyphenol content; 2) the DPPH (1,1-diphenyl-2-picrylhydrazyl) spectrophotometric assay and the Trolox Equivalent Antioxidant Capacity (TEAC) spectrophotometric assay for measuring the antioxidant activity of samples; 3) High Performance Thin Layer Chromatography for separation of phenolic substances and assessment of the associated antioxidant activity; 4) electrochemical detection by using a biosensor. Although all the approaches show some limitations, this battery of tests offers a more reliable body of data on the antioxidant activity of vine derivatives.